Preparation And Supercapacitor Performance Of Core-shell Ni Based Structure Nico₂O₄-PANI Composite

In recent years,with the rapid development of science and technology,the global energy demand has grown continuously,which calls for the development of high-performance,low-cost and environmentally friendly energy conversion/storage systems.Because of its high specific capacitance,strong cycling ability and fast charge and discharge rate,supercapacitors have become the research hotspot of new energy modes,in which electrode materials have been widely studied as the key factors to determine the electrochemical performance of supercapacitors.NiCo₂O₄ and polyaniline?PANI?,respectively as typical bimetallic oxides and conducting polymers,have already shown excellent properties in the study of pseudocapacitive electrode materials,but both of the two materials have their own shortcomings,which limit their development in practical applications.In order to overcome the shortcomings of these two materials.This study selected nickel foam as the substrate,and the core-shell structure NiCo₂O₄-PANI composites with ultra-high performance were synthesized directly on the surface of the Ni foam.The as-prepared materials were characterized and tested to analyze their electrochemical properties in the application of supercapacitor electrode material.The details are as follows:?1?NiCo₂O₄ nanomaterials were synthesized on the surface of nickel foam with hydrothermal method.Then the core-shell structure NiCo₂O₄-PANI composites were prepared by in situ polymerization with HCl as proton acid doping at low temperature.Characterization analysis showed that the core NiCo₂O₄ had a standard crystal morphology,and the flake self-assembled attached to the surface of nickel foam with a sphere size of about 5?m.The crystallinity of the shell PANI is weak,PANI with weak crystallinity are uniformly coated NiCo₂O₄ crystal spheres and a dense film is formed on their surface,which achieved the co-doping of H⁺,Ni²⁺/Ni³⁺,Co²⁺/Co³⁺in polyaniline.?2?Electrochemical performance tests of NiCo₂O₄-PANI composites were carried out using electrochemical workstation,including three-electrode test and two-electrode test.The specific capacitance of the NiCo₂O₄-PANI electrode material was 3108 F g^-1 at the current density of 1 mA cm^-2 in three-electrode test system,reached five times higher than that of the NiCo₂O₄ electrode material.The cycling stability was tested at a current density of 20 mA cm^-2,after 1000 continuous charge/discharge tests,the specific capacitance decay was less than 4%,showing excellent electrochemical performance.EIS impedance spectroscopy also showed that NiCo₂O₄-PANI composites had lower impedance and superior ionic diffusivity.The energy density of NiCo₂O₄-PANI//AC asymmetric electrode can reach 77.57 Wh kg^-1 with the power density of 800 W kg^-1.The results showed that the nickel-based core-shell structure NiCo₂O₄-PANI composites synthesized in this study showed ultra-high specific capacitance while still maintaining very excellent cycling stability,which showed great potential and development prospects in the study of supercapacitor electrode materials.